Sounds to me like you have a spinal or pelvic joint either locked or out of place.
When either of these things happen, the muscles go all defensive to protect the joint, and soon become very tight and sore, giving the pain you describe.
I have had many occurrences of a similar nature.
See a physio or chiro to have all of these joints checked out for alignment.
MRIs don't take into account soft tissue trauma, an area far more likely to be a cause of pain.
Everything thing we do depends on our muscles, yet we don't look after them, and don't think about them when we get ill.
I've learnt the hard way!
My biggest success in relieving muscle pain is very simple, cheap, harmless and fast acting.
I take a lot of magnesium chloride, mixed with water and used as my sole water intake. Works when you have a magnesium deficiency, which most people have.
You can get tablets and powders, but the liquid is the fastest acting.
After getting your joints checked, and corrected, get a remedial massage to begin the healing process for your muscles.